diff --git a/sphinx/domains/cpp.py b/sphinx/domains/cpp.py
index 7dd1d0c03..882c8275f 100644
--- a/sphinx/domains/cpp.py
+++ b/sphinx/domains/cpp.py
@@ -6537,7 +6537,14 @@ class DefinitionParser(BaseParser):
                 declSpecs = self._parse_decl_specs(outer=outer, typed=False)
                 decl = self._parse_declarator(named=True, paramMode=outer,
                                               typed=False)
-                self.assert_end(allowSemicolon=True)
+                must_end = True
+                if outer == 'function':
+                    # Allow trailing requires on constructors
+                    self.skip_ws()
+                    if re.compile(r'requires\b').match(self.definition, self.pos):
+                        must_end = False
+                if must_end:
+                    self.assert_end(allowSemicolon=True)
             except DefinitionError as exUntyped:
                 if outer == 'type':
                     desc = "If just a name"
diff --git a/tests/test_domain_cpp.py b/tests/test_domain_cpp.py
index 9159b1851..c88111e89 100644
--- a/tests/test_domain_cpp.py
+++ b/tests/test_domain_cpp.py
@@ -893,6 +893,8 @@ def test_domain_cpp_ast_requires_clauses():
           {4: 'I0EIQoo1Aoo1B1CE1fvv'})
     check('function', 'void f() requires A || B || C',
           {4: 'IQoo1Aoo1B1CE1fv'})
+    check('function', 'Foo() requires A || B || C',
+          {4: 'IQoo1Aoo1B1CE3Foov'})
     check('function', 'template<typename T> requires A && B || C and D void f()',
           {4: 'I0EIQooaa1A1Baa1C1DE1fvv'})
     check('function',